1. Field of the Invention
The invention provides novel PPL materials and compositions and more sensitive tests for predicting and diagnosing allergy or hypersensitivity to penicillin in humans or other animals by skin testing with the improved PPL compositions of the invention.
2. Discussion of the Prior Art
Since the introduction of penicillins for therapeutic treatment of infections in humans and other animals, a variety of allergic reactions have been observed; the most serious of these reactions is anaphylactic shock, which is estimated to be the cause of several hundred deaths in the United States each year. The possibility of non-fatal anaphylaxis and urticarial reactions, which are much more common than fatal anaphylaxis, also is a matter of serious concern for the physician considering the treatment of a patient with penicillins.
Therefore, much research effort has been devoted to the development of reliable tests predictive of human allergic response or hypersensitivity to penicillin. As the result, certain skin tests have been described in the literature and are under study clinically. One such test generally involves scratching the skin in an area on which a test solution has been placed, or intradermally injecting the test solution, and observing for a positive reaction--i.e., a wheal-and-flare reaction around the scratch or injection sites formed within 15 minutes. More sensitive skin tests involve the inntradermal injection of solutions containing (1) PPL and (2) MDM (minon determinant mixtures) compositions.
The chemistry underlying the mechanism by which penicillin may trigger allergic reactions in humans and the details of the state of the art in "scratch" and "intradermal" skin tests is extensively set forth in the literature. The following are intended only as representative citations which provide useful technical background in the field of this invention:
"Immunological Mechanisms of Penicillin Allergy" PA1 B. B. Levine; J. New England Medicine, 275:1115 (1966) PA1 "The Nature of the Antigen-Antibody Complexes Initiating the Specific Wheal-and-Flare Reaction in Sensitized Man" PA1 B. B. Levine, A. P. Redmond; J. Clinical Investigation, 47:556 (1968) PA1 "Predictions of Penicillin Allergy by Immunological Tests" PA1 B. B. Levine, D. M. Zolov; J. of Allergy, 43:4:231 (1969) PA1 "Drug Allergy" PA1 B. B. Levine; Reprint of Edited Remarks presented at seminar co-sponsored by Johns Hopkins U., Am. Acad. of Allergy and NIH (1971) PA1 "Skin Rashes With Penicillin Therapy: Current Management" PA1 B. B. Levine; New England Journal of Medicine (1971) PA1 "A Guide to Skin Testing for Penicillin Allergy" PA1 N. F. Adkinson, Jr., Resident and Staff Physician at Johns Hopkins U. (1977) PA1 See also U.S. Pat. Nos. 3,867,365 and 3,979,508 issued to Stahmann and Wagle.
U.S. Pat. No. 3,867,365, noted above, describes one prior art PPL material used in penicillin allergy skin tests, and it is believed that such compounds may have been commercialized. The patented compositions over which my compositions are an improvement comprise BPO conjugates of a heterogeneous mixture of random polylysine polymers said to have from about 12 to 102 or more lysine units linked in the polymer chain.
In prior studies, such as those cited above, it has also been shown that some patients who are given penicillin therapeutically develop IgE antibodies to certain haptens which are formed from the reaction of the penicillin with tissue proteins. These include the benzylpenicilloyl (BPO) hapten, whose structure is well known, and certain "minor determinant" haptens whose structures are not yet known.
IgE antibodies are known to mediate anaphylactic and other immediate allergic reactions to penicillin in man. These reactions are frequently severe, causing diffuse rash, difficulty in breathing, abdominal cramps and fainting, hypotension and arrythmia. They are capable of causing death due to cardiovascular collapse, ventricular arrythmia and/or respiratory obstruction.
Skin tests with various materials derived from penicillin have been shown to be positive in the presence of these IgE antibodies, and thus serve as a predictive test for severe penicillin allergy. The skin test compositions currently in use include benzylpenicilloyl-polylysine (BPL), which detects IgE antibodies specific for the BPO haptenic group, and the MDM, which detects IgE antibodies specific for the minor determinants.
With respect to my new PPL materials, I have observed a number of significant improvements over the prior art. First, my PPL materials are homogeneous, high purity materials which offer higher reproducibility from lot to lot than is provided by heterogeneous polylysine conjugates of the prior art. The new PPL materials of this invention also are substantially free from low molecular weight impurities (polylysine.sub.2 and/or polylysine.sub.3) and, therefore, minimize the chance of diffusion of compound from the test site into the bloodstream with the attendant possibility of constitutional reactions. Additionally, my relatively low molecular weight, B.sub.4-13 --L.sub.6-12, materials would have a lower degree of immunogenicity than the higher molecular weight PPL conjugates of the prior art, and, thus, are less likely to induce allergy in a test subject. Further my PPL materials are of a molecular weight which allows sufficient diffusion in the skin from an intradermal or prick test site to give an intense wheal-and-flare reaction. By contrast, high molecular weight conjugates may diffuse less well in about one-fourth to one-third of patients and, thus, may not give a recognizably positive skin test in some allergic patients (Levine and Fellner, Journal of Allergy, 36:342-52 (1965)).
In view of the possibly catastrophic consequences of observing a negative response in a patient who is actually allergic to penicillin, it is critical that the most sensitive and highly reliable allergy tests be made clinically available.
Further, the use of the most sensitive test is of importance when doing prick or scratch tests. These are much more convenient but less sensitive than intradermal tests. Thus, more sensitive test materials permit the use of a prick test.
Accordingly, the principal objective of my invention is to provide a more sensitive and reproducible skin test for penicillin allergy using improved PPL preparations. Another purpose is to provide novel PPL and MDM compounds and compositions for use in skin testing for prediction or diagnosis of penicillin allergic reaction or hypersensitivity.